For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used?
(A) 1.0 to 1.2 A/mm2
(B) 1.5 to 2.0 A/mm2
(C) 2.2 to 3.2 A/mm2
(D) 3.2 to 4.2 A/mm2
The rupture of co-valent bonds will occur when the electric field is__________________?
(A) 100 V/cm
(B) 6 V/cm
(C) 1000 V/cm
(D) More than 105 V/cm
The cold rolled grain oriented steel has _________ permeability in the direction of the grain orientation?
(A) minimum
(B) maximum
(C) nil
(D) none of the above
Cylindrical windings using circular conductors, employed in transformers, are_____________?
(A) single layered
(B) double layered
(C) multi-layered
(D) none of the above
Multi-layer helical windings are commonly used in the transformers as high voltage windings_______________?
(A) upto 20 kV
(B) upto 50 kV
(C) upto 80 kV
(D) for 110 kV and above
The cold rolled grain oriented steel has ___________ permeability in the direction of the grain orientation?
(A) minimum
(B) maximum
(C) nil
(D) none of the above
Helical windings are used in________________?
(A) distribution transformers
(B) power transformers
(C) shell type transformers
(D) none of the above
Disc windings are primarily used in_____________-?
(A) short capacity transformers
(B) medium capacity transformers
(C) high capacity transformers
(D) any of the above
The forced oil and air circulation method is usual one for transformers of capacities____________?
(A) upto 5 MVA
(B) upto 10 MVA
(C) upto 20 MVA
(D) 30 MVA upwards
The heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ?
(A) Corrugations
(B) Fins
(C) Tubes
(D) Radiator tanks
(D) All of the above